A Novel Approach for Transmission of 56 Gbit/s NRZ Signal in Access Network Using Spectrum Slicing Technique

We present the spectrum slicing and stitching concept for high-capacity low optics complexity optical access networks. Spectrum slicing and stitching of a 56 Gbit/s NRZ electrical signal is experimentally demonstrated for the first time. We present the spectrum slicing and stitching concept for high-capacity low optics complexity optical access networks. Spectrum slicing and stitching of a 56 Gbit/s NRZ electrical signal is experimentally demonstrated for the first time

Binomial Number System

This paper presents and first scientifically substantiates the generalized theory of binomial number systems (BNS) and the method of their formation for reliable digital signal processing (DSP), transmission, and data storage. The method is obtained based on the general theory of positional number systems (PNS) with conditions and number functions for converting BNS with a binary alphabet, also allowing to generate matrix BNS, linear-cyclic, and multivalued number systems. Generated by BNS, binomial numbers possess the error detection property. A characteristic property of binomial numbers is the ability, on their basis, to form various combinatorial configurations based on the binomial coefficients, e.g., compositions or constant-weight (CW) codes. The theory of positional binary BNS construction and generation of binary binomial numbers are proposed. The basic properties and possible areas of application of BNS researched, particularly for the formation and numbering of combinatorial objects, are indicated. The CW binomial code is designed based on binary binomial numbers with variable code lengths. BNS is efficiently used to develop error detection digital devices and has the property of compressing information

Linear Regression vs. Deep Learning for Signal Quality Monitoring in Coherent Optical Systems

Error vector magnitude (EVM) is a metric for assessing the quality of m-ary quadrature amplitude modulation (mQAM) signals. Recently proposed deep learning techniques, e.g., feedforward neural networks (FFNNs) -based EVM estimation scheme leverage fast signal quality monitoring in coherent optical communication systems. Such a scheme estimates EVM from amplitude histograms (AHs) of short signal sequences captured before carrier phase recovery (CPR). In this work, we explore further complexity reduction by proposing a simple linear regression (LR) -based EVM monitoring method. We systematically compare the performance of the proposed method with the FFNN-based scheme and demonstrate its capability to infer EVM from an AH when the modulation format information is known in advance. We perform both simulation and experiment to show that the LR-based EVM estimation method achieves a comparable accuracy as the FFNN-based scheme. The technique can be embedded with modulation format identification modules to provide comprehensive signal information. Therefore, this work paves the way to design a fast-learning scheme with parsimony as a future intelligent OPM enabler

FIBRE OPTICAL COUPLER SIMULATION BY COMSOL MULTIPHYSICS SOFTWARE

Funding: The research has been supported by the European Regional Development Fund project No.1.1.1.1/18/A/068. The Institute of Solid State Physics, University of Latvia as a Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.The paper presents a simulation model developed for a special optical coupler intended for coupling radiation from signal and pump sources used for the realization of cladding-pumped doped fibre amplifiers. The model is developed in COMSOL Multiphysics and used to assess the pumping efficiency for different side pumping angles and different numbers of electromagnetic modes. The obtained results show that the highest pumping efficiency, above 75 %, is achieved for 5–14 modes when two fibres representing the pump source and the signal source form a 10-degree angle between their central axes. The search for the optimal number of modes corresponds to the development trend in optical coupler technology where the multimode pumping by light-emitting diode (LED) replaces the classical scheme with a single-mode pumping by a laser diode (LD). © 2022 Sciendo. All rights reserved. --//-- This is an open access article Elsts E., Supe A., Spolitis S., Zakis K., Olonkins S., Udalcovs A., Murnieks R., Senkans U., Prigunovs D., Gegere L., Draguns K., Lukosevics I., Ozolins O., Grube J., Bobrovs V. FIBRE OPTICAL COUPLER SIMULATION BY COMSOL MULTIPHYSICS SOFTWARE (2022) Latvian Journal of Physics and Technical Sciences, 59 (5), pp. 3 - 14, DOI: 10.2478/lpts-2022-0036 published under the CC BY-NC-ND 4.0 licence.ERDF No.1.1.1.1/18/A/068; The Institute of Solid State Physics, University of Latvia as a Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2

Coronavirus-like all-angle all-polarization broadband scatterer

This is the final version. Available on open access from Nature Research via the DOI in this recordData availability: All data generated or analyzed during this study are included in this published article. The modeling script is available online: https://zenodo.org/record/6962448#.ZA8jvS8w2LcCreeping waves traveling around a volumetric electromagnetic scatterer provide a significant contribution to its radar cross-section. While quite a few efforts were devoted to suppressing creeping waves as a part of radar countermeasures, here we utilize specially engineered creeping waves to our advantage to create broadband, all-angle, and polarization scatterers. Metalized spherical surfaces, patterned with corona virus-like spikes are designed to provide a broadband constructive interference between the specular reflection and creeping waves, elevating the scattering cross-section. The demonstrated miniature corona scatterers utilize both resonant cascading phenomena and traveling wave interference to tailor electromagnetic interactions, outperforming a resonant dipole in terms of amplitude and bandwidth quite significantly. Our experimental samples are fabricated with an additive manufacturing technique, where a 3D-printed plastic skeleton is subsequently metalized. Micron-thick layers allow governing electromagnetic interactions as if the entire object was made of solid metal. Lightweight, all-angle, all-polarization, and broadband compact scatterers such as these, reported here, have numerous applications, including radar deception, electromagnetic beckoning, and many others.Department of the Navy, Office of Naval Research GlobalRRF project Latvian Quantum Technologies InitiativeRoyal Academy of Engineerin

FPGA-Implemented Fractal Decoder with Forward Error Correction in Short-Reach Optical Interconnects

Forward error correction (FEC) codes combined with high-order modulator formats, i.e., coded modulation (CM), are essential in optical communication networks to achieve highly efficient and reliable communication. The task of providing additional error control in the design of CM systems with high-performance requirements remains urgent. As an additional control of CM systems, we propose to use indivisible error detection codes based on a positional number system. In this work, we evaluated the indivisible code using the average probability method (APM) for the binary symmetric channel (BSC), which has the simplicity, versatility and reliability of the estimate, which is close to reality. The APM allows for evaluation and compares indivisible codes according to parameters of correct transmission, and detectable and undetectable errors. Indivisible codes allow for the end-to-end (E2E) control of the transmission and processing of information in digital systems and design devices with a regular structure and high speed. This study researched a fractal decoder device for additional error control, implemented in field-programmable gate array (FPGA) software with FEC for short-reach optical interconnects with multilevel pulse amplitude (PAM-M) modulated with Gray code mapping. Indivisible codes with natural redundancy require far fewer hardware costs to develop and implement encoding and decoding devices with a sufficiently high error detection efficiency. We achieved a reduction in hardware costs for a fractal decoder by using the fractal property of the indivisible code from 10% to 30% for different n while receiving the reciprocal of the golden ratio

Estimating the indivisible error detecting сodes based on an average probability method

Given the need to improve the efficiency of data transfer, there are requirements to ensure their reliability and quality under interference. One way to improve data transfer efficiency is to use noise-resistant codes, which include a closed-form expression of the Fibonacci code, a parity check code, and a constant weight code. The result of applying these types of coding produces interference-resistant end-to-end processing and transmission of information, which is a promising approach to improving the efficiency of telecommunications systems in today's environment. This paper reports the estimation of the error detecting code capability of the Fibonacci code in a closed-form expression, as well as its comparative characteristic with a parity check code and a constant weight code for a binary symmetrical channel without memory. To assess an error detecting capability of the Fibonacci code in a closed-form expression, the probability of Fibonacci code combinations moving to the proper, allowable, and prohibited classes has been determined. The comparative characteristic of the indivisible error-detecting codes is based on an average probability method, for the criterion of an undetectable error probability, employing the MATLAB and Python software. The method has demonstrated the simplicity, versatility, and reliability of estimation, which is close to reality. The probability of an undetectable error in the Fibonacci code in a closed-form expression is V=5×10-7; in a code with parity check, V=7.7×10-15; and in a constant weight code, V=1.9×10-15, at p10=3×10-9. The use of the average probability method makes it possible to effectively use indivisible codes for detecting errors in telecommunications systems